Front end construction for rock drills



July 31, 1934. J. c. CURTIS 1,963,376

FRONT END CONSTRUCTION FOR ROCK DRILLS Filed Sept. 26, 1931 [M /L5 0 767 40 30 zi' 27 M14 f JOHN 6. age 775 INVENTOR LQM ATTORNEY Patented July31, 1934 v z FRONT END CONSTRUCTION FOR ROCK DRILLS John 0. Curtis,Cleveland, Ohio, assignor to The Cleveland Rock Drill Company,Cleveland, Ohio, a corporation of Ohio Application September 26, 1931,Serial No. 565328 2 Claims. (Cl. 121-32) This invention relates to rockdrills but more the several views, the rock drillcomprisesa-cylparticularly to the front bearing construction for inder10 having reciprocabletherein a hammer 11 rock drills of the hammertype. being formed with an extension or stem 12. 'The Considerabletrouble has been experienced with front cylinder is provided with anenlarged counrock drills having a hammer formed of differenterbore 13disposed in axial alignment with the tial diameters. It has been foundthat due to main cylinder bore 14. Within the enlarged the'torqueapplied to the hammer during its rearcounterbore 13 and with a pressedfit engagement ward stroke, the hammer stem is forced radially therein,there is a sleeve or spacer 16 provided against its bearing. In thecommon practice, intermediate its ends with an external flange 1'7 thatbearing is usually of the stationary type afheld in abutting relationwith the outer endof fording a reciprocatory as well as a rotary bearthecylinder and the outer end of the chuck ing for the hammer stem and isnecessarily of a housing 18. Rotatably mounted within the rather shortlength to accommodate the other spacer 16, there is a bushing or chuck19 having working parts of the mechanism. The torque its penetrationtherein limited byan external M applied on the hammer stem as well asits longiflange 20 abutting against the outer end of the 'tudinaldisplacement creates a frictional resistspacer 16 and being formed witha projection 21 ance which has the tendency to cause the scoringrotatably mounted within a bore 22 of 1 the chuck of the stem within itsbearing. housing 18. The rearward end 23 of the chuck It is an object ofthis invention to provide a 191s adequately machined to slidably receiveand i rock drill with adequate bearing means for the guide the hammerstem Band has its front end the invention. clamped by either theshoulder 31 or 30.

"- bols designate corresponding parts throughout alignmentwith thecylinder bore 14.

hammer stem thus overcoming the scoring of the provided with a pluralityof inwardly prostem and therefore reducing the cost of operajecting ribsor flutes 24 capable of engagetion, ment with the splines 25 which areprovided Another object of this invention is to provide on the hammerstem 12, preventing thereby arela rock drill with a readily removablehammer ative rotation of the chuck with the hammer. stem bearing thusovercoming the often encoun- Internally disposed within the projection21, tered difficulty in replacing such a part which there is a pluralityof flutes 26,.similar to the in usual construction is generally with apressed flutes 24. Within the chuck housing bore 27, fitengagementwithin the front end of the cylthere is rotatably mounted therein achuck jaw 30 inder. 28 formed with an external flange 29 havingone Otherobjects more or less ancillary to the foreor" its sides in abuttingrelation with a shoulder going and the manner in which the various ob-30 formed at the intersection of the bore 21 with jects are attainedreside in the specific constructhe bore 27. lhe other side of the flange29 is tion and aggroupment of the elements'peculiar to capable ofengagement with the outer end of the. this structure, as will becomeapparent from a chuck 19. The bore 21 is of sufficient depth to' morecomplete examination of this specification, allow an adequate clearancebetween the outer in the claims of which there are assembled certain endof the chuck l9 and the adjacent side of the specific combinations ofparts and specific conchuck jaw flange 29, allowing thereby the rotationstructions indicative of the scope and spirit of of the chuck l9 andchuck jaw 28 W t ut bei In the drawing which illustrates a preferredCircumferentiaily disposed on the end of the embodiment of theinvention: chuck jaw 28, there is a plurality of splines 33 Fig. 1 is alongitudinal sectional view of the capable of engagement with the flutes26 of the front end of a'rock drill, illustrating the invenchuck 19 toprevent the rotation of the chuck tion. 19 with respect to the chuck jaw28. The for- 00 Fig. 2 is a cross sectional view taken on a plan wardend of the chuck jaw 28 is provided with a indicated by line 2-2 inFigure 1. plurality of jaws 34 engageable with the corre- Fig. 3 is aview similar to Fig. 2 but taken on spending jaws 35 of the chuck key 36rotatably a plan indicated by line 3-3 in Figure 1. disposed within thefront portion of the chuck 350 Fig. 4 is a front elevational view partlyin housing bore 27 and maintained therein by the section, inwardlyprojecting flange 38. The key 36 is Fig. 5 is a view similar to Figure 1illustrating manufactured to .allow the passage of the lug amodification of the invention. steel or tool 37 which is slidably butnon-rotatably Referring to the drawing, in which like symmounted withinthe chuck jaw bore 39 in axial In the modification of the invention,(Fig. 5) the locking means for the chuck 19 and chuck jaw 28 is attainedwith a screw threaded socket 40 formed in the chuck 19 and acorresponding screw threaded plug 41 formed at the rearward end of thechuck jaw 28. It is obvious that a locking means similar to the jaws 34and 35 could be used without departing from the spirit of the invention.

In the operation of the rock drill, the hammer 11 is reciprocated withinthe cylinder 10 by fluid pressure controlled by a valve mechanism of anysuitable type. Toward the end of its rearward stroke, the hammer isdelivering a blow to the steel or tool 38 driving consequently the toolinto the substance being drilled. During its rearward stroke, the hammer11 is subjected to a rotative movement impelled thereto by any suitableratchet mechanism as commonly used in machines of this type. Obviouslythis rotative movement will be transmitted to the chuck 19 by theengagement of the hammer splines 25 with the flutes 24 and to the drillsteel 38 by the engagement of the flutes 26 with the splines 33.

Heretofore in devices of this character, the piston stem 12 wasreciprocatively mounted within a short stationary bushing which had thedifliculty of maintaining an exact axial alignment of the stem 12 withthe cylinder bore 14 and consequently increasing the frictionalresistance within said bushing and censequently scoring the stem 12. Inthis improved construction, the guiding bushing for the hammer stem 12is rotatably mounted within a long and eflicient spacer 16. The torqueimparted to the hammer is distributed on the full exterior surface ofthe chuck 19 which can be made of softer material than the spacer 16.The chuck 19 may for instance be manufactured of brass, thus preventingany noticeable wear within the spacer 16 and overcoming thereby thedifiicult replacement of that spacer from its pressed fitted engagementwith the cylinder.

Although the foregoing description is necessarily of a detailedcharacter, in order to completely set forth the invention, it is to beunderstood that the specific terminology is not intended to berestrictive or confining and it is to be further understood that variousrearrangements of parts and modification of structural detail may beresorted to without departing from the scope or spirit of the inventionas herein claimed.

I claim:

1. In a rock drill, the combination with a cylinder having a fluidactuated hammer reciprocable therein and capable of rotation responsiveto its reciprocation, said piston being formed with a head and a stern,external splines on the front end portion of said stem, of a stationaryremovable bushing within said cylinder, of a sleeved member rotatablewithin the entire length of said bushing through which said piston stemis free to slide, of a front housing, of a chuck member rotatable withinsaid housing formed with external splines disposed on the rear endportion thereof, a duality of sets of internal splines within saidsleeved member, one of said sets of splines being capable ofinterengagement with the splines of said piston stern and the other ofsaid sets of splines being capable of interengagement with the splinesof said chuck member for transmitting the rotation of said piston tosaid sleeved and chuck members, an internal portion of said sleevedmember being engageable with the unsplined portion of said piston stemfor guiding the latter in axial alignment with said cylinder and takingthe wear resulting therefrom, the external circumferential wall of saidsleeved member 00- operating with the external wall of said bushing fortaking the wear resulting from the rotation of said piston.

2. In a rock drill, the combination with a cylinder having a fluidactuated hammer reciprocable therein and capable of rotation responsiveto its reciprocation, said piston being formed with a head and stem, ofa stationary removable bushing within said cylinder, of a sleeved memberrotatable within the entire length of said bushings through which saidpiston stem is free to slide, external splines disposed Within the frontend portion of said piston stem, internal splines disposed within themiddle portion of said sleeve member capable of interengagement with therotation of the latter to the former, a rotatable chuck member formedwith external splines engageable with other internal splines providedwithin the front end portion of said sleeved member for transmitting therotation of the latter to said chuck member, the rearward internalportion of said sleeved member being engageable with the correspondingportion of said piston stem for guiding the latter in axial alignment Iwith said cylinder and taking the wear resulting therefrom, the externalcircumferential wall of said sleeved member cooperating with theinternal wall of said bushing for taking the wear resulting from therotation of said piston, the rear 7 end of said sleeved member beingexposed to the pressure fluid admitted on the front end of said pistonhead during the actuation of the latter, the area of the exposed end ofsaid sleeved member being less than that of the front of said pistonhead.

JOHN C. CURTIS.

splines of said piston stem for transmitting the

